<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div style="margin-left: 400px">
    <h3>if 使用</h3>
    <p th:if="${sex=='m'}">性别是男</p>
    <p th:if="${isLogin}">已经登录系统</p>
    <p th:if="${age>20}">年龄大于20</p>
    <!--空字符是true-->
    <p th:if="${name}">name是""</p>
    <!--null是false-->
    <p th:if="${isOld}">isOld是null</p>
</div>
<br/>
<br/>
<div style="margin-left: 400px">
    <h3>unless: 判断条件为false 显示标签体内容</h3>
    <p th:unless="${sex=='f'}">性别是男的</p>
    <p th:unless="${isLogin}">登录系统</p>
    <p th:unless="${isOld}">isOld是个null</p>
</div>
</body>
</html>